Structural basis for distinct operational modes and protease activation in AAA plus protease Lon
Structural basis for distinct operational modes and protease activation in AAA plus protease Lon
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DOI：
10.1126/sciadv.aba8404
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发表时间：
2020-05-01
期刊：
影响因子：
13.6
通讯作者：
Lander, Gabriel C.
中科院分区：
文献类型：
--
作者：
Shin, Mia;Puchades, Cristina;Lander, Gabriel C.
AAA+蛋白易位酶的底物结合结构揭示了保守的不对称螺旋楼梯结构，其中连续的ATP水解循环驱动交接底物易位。然而，这种构象不太可能代表这些酶的完整构象景观，因为生化研究表明不同的构象状态取决于底物的存在或不存在。在这里，我们使用冷冻电子显微镜来确定鼠疫耶尔森氏菌 Lon AAA+ 蛋白酶在底物不存在和存在的情况下的结构，揭示两种不同操作模式的机制基础。在没有底物的情况下，Lon 采用左手“开放”螺旋组织，具有自抑制蛋白水解活性位点。添加底物后，Lon 会进行重组，以组装具有酶活性、具有活性蛋白酶位点的右手“闭合”构象异构体。这些发现定义了加工不同蛋白质底物所需的操作可塑性的机械原理。
Substrate-bound structures of AAA+ protein translocases reveal a conserved asymmetric spiral staircase architecture wherein a sequential ATP hydrolysis cycle drives hand-over-hand substrate translocation. However, this configuration is unlikely to represent the full conformational landscape of these enzymes, as biochemical studies suggest distinct conformational states depending on the presence or absence of substrate. Here, we used cryo-electron microscopy to determine structures of the Yersinia pestis Lon AAA+ protease in the absence and presence of substrate, uncovering the mechanistic basis for two distinct operational modes. In the absence of substrate, Lon adopts a left-handed, "open" spiral organization with autoinhibited proteolytic active sites. Upon the addition of substrate, Lon undergoes a reorganization to assemble an enzymatically active, right-handed "closed" conformer with active protease sites. These findings define the mechanistic principles underlying the operational plasticity required for processing diverse protein substrates.